Power Semiconductor Substrate Dimples for Stronger Sintered Bonding
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Solution Overview
Problem
The existing bonding structures using sintered metal materials for power semiconductor devices face issues with non-uniform pressure distribution, leading to reduced bonding life and increased risk of semiconductor element displacement, peeling, and heat radiation property degradation due to uneven surface roughness and insufficient pressure application.
Innovation Solution
The formation of dimples on the substrate surface by laser processing outside the heat generation unit of the semiconductor element, which increases the bonding area and provides an anchoring effect in all directions, enhancing bonding strength and preventing peeling from affecting heat radiation properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If sintered metal bonding material is used instead of solder, then heat resistant property is improved, but bonding life is degraded due to non-uniform pressure distribution
Solution Approach 1:
The substrate surface is modified to have different local properties: dimples are formed in specific regions to increase bonding area and improve pressure distribution, while the central region under the heat generation unit maintains a different characteristics to prevent peeling and protect heat radiation properties. This local differentiation resolves the contradiction by allowing optimized bonding in peripheral areas while preserving thermal performance in the central area.
2Reliability
If pressure is increased to improve bonding life, then bonding strength is improved, but semiconductor element damage increases
Solution Approach 1:
The bonding area is segmented into different functional zones: peripheral regions with dimples that accommodate higher pressure for improved bonding, and a central region under the heat generation unit that is protected from excessive pressure. This segmentation allows the system to achieve strong bonding where needed while protecting the semiconductor element from damage.
3Reliability
If surface roughness is increased to improve bonding area, then bonding strength is improved, but pressure distribution becomes non-uniform
Solution Approach 1:
The dimples are formed in advance on the substrate surface before bonding, creating predetermined regions that guide pressure distribution during the bonding process. This preliminary action ensures that when pressure is applied, it is distributed uniformly across the bonding interface, preventing the non-uniform pressure distribution that would otherwise result from simple surface roughness increases.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach results in improved bonding strength and extended product life by ensuring uniform pressure distribution and anchoring effects, while maintaining heat radiation performance, even under thermal stress and mechanical displacement risks.
Implementation Method 1
The sintered metal bonding material utilizes a phenomenon in which the metal fine particles are sintered at a temperature lower than a melting point of a metal forming the metal fine particles so as to achieve metal bonding to a member to be bonded.
Implementation Method 2
In a state after the bonding, the metal fine particles are diffusively bonded to each other, and metallization of an element and a top of a substrate to be mounted with the element are also diffusively bonded to each other.
Implementation Method 3
a plurality of dimples are formed by laser processing in the first surface of the substrate
Data Source
AI summary
A power semiconductor device includes a substrate and a semiconductor element bonded onto a first surface of the substrate through use of a sintered metal bonding material. The substrate has a plurality of dimples formed in the first surface and located outside a location immediately below a heat generation unit of the semiconductor element. The sintered metal bonding material is supplied onto the substrate after the formation of the dimples, and the semiconductor element is bonded to the substrate through application of heat and a pressure thereto.